Matip, 24, will join the Reds on a Bosman this summer and become Klopp's second permanent signing.

"I know in England it is really difficult to sign a player without paying a transfer fee, but I thought it cannot be a reason not to take him only because you cannot put a number behind his name," Klopp said.

"If you asked in Germany what other clubs would have paid for him had he still been under contract, you can just pick a number."